[jrelliott]

Have you tested voltage at the bulbs that are not coming on? That would be the first place to start. If you have voltage measure the resistance from the bulb socket to ground. Turn off the lights before you make this last test can ruin the meter. I ran separate ground wires from the tail light housing and head light housings to chassis ground inside the harnesses so would not be seen. The ground connection had a soldered on terminal lug with a star washer between the lug and the chassis to insure a good connection. On the headlights had to remove the original connections at the conduits to headlight and using slip connectors on the head light wires. This prevented any shorting and flickering headlights.